Signaling system



. Re. 16,141 H. c. EGERTQN SIGNALING sYsTEu Original Filed Dec. 27, 1918 QZSEUMQ Reissued Aug.` 25, 1925.

UNITED STATES PATENTV OFFICE.

HENRY G'. EGERTON, OF MADISON, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OIF NEW YORK,v N.

Y., A CORPORATION 0F NEW YORK.

SIGNALING SYSTEM.

Original No. 1,400,039, dated December 13, 1921, Serial No. 268,482, filed December 27, 1918. Application for reissue filed April 30,

To all whom t may concern.'

Be it known that I, HENRY C. EGERTON, a citizen of the UnitedStates, residing at Madison, in the county of Morris, State of New Jersey, have invented certain new and useful Improvements in Signaling Systems, of which the following is a full, clear, concise and exact description.

'Ifhis inventionrelates to electric signal-l ing systems, and more particularly to the production and utilization of impulses 'for synchronizing purposes.

The principal object of this invention is to combine a plurality ofy high frequency currents in such a manner that the resultant frequency or beat oscillations may be employed to keep a plurality of movable members in unison or synchronism, this condition to be insured regardless of whether signaling impulses are being transmitted or not.

The invention contemplates the employment of two alternating current sources giving different frequencies connected in series or parallel and arranged to feed into a re- `peater or line circuit. If two alternating current sources having slightly different frequencies are impressed upon a line circuit, beat oscillations are produced the most 'important of which' have a frequency equal to the difference in the frequencies of the twov sources. If the two different frequencies are sent into a vacuum tube repeater, not only the original frequencies come out, but also a low electrical oscillation, the frequency of which depends upon the number of beats occurring due to 'combining the two currents of higher frequencies. It is this low frequency current which it is pro dosed to use for maintaining synchronism. hese beats may be manifested as a sound or noise in a receiving instrument or as illustrated in the present application, they may be employed for performing work such as the operation of an electromagnet. The production of beat oscillations in the present instance is accomplished byl generating two frequencies, for example, oscillations of 400 and 404 cycles and these frequencies may in a telegraph system be superimposed on the signaling currents without interfering with the effective transmission of the latter.

The above and other objects of this invention will be set forth in the vfollowing if transmitter contacts 11 and ground 42,

1923. serial No'. 635,714.

description and claims and will be more readily understood by reference to the `accompanying drawing wherein the invention is disclosed as applied to a printing telegraph system of the rotarydistributer type.

In the accompanying drawing A represents a sending station and B a receiving station. At station A there is provided one or more impulse transmitters 10, each comprising a group of selectively operable transmitter contacts 11,12, 13, 14 and 15. vThe contacts are connected to a source `of A.C. signaling current 45 and are adapted when actuated to connect source of current 45 to corresponding segments 16,17, 18, 19 and 20 respectively of distributer 21.

The transmitter 1() may be of the keyboard type or it may consist o-f an automatic transmitter operated by a perforated tape or the like. If an automatic transmitter is employed the segments 70 and 71 may bje used to connect battery 72 over the distributer brush 23 to a suitable'magnet (not shown) for advancing the perforated type.

A distributerarm 22 carries a brush 23 which is adapted to sweep over the segments ofthe distributer face and connect the segments of each group sequentially with a common ring 24 which, as illustrated, cornprises a plurality of segments strapped'together. The distributer brush arm 22 is preferably normally under tension tending to rotate and its rate of travel may be governed by electromagnet 25 through the instrumentality of the escapement mechanism 26 and ratchet 27 or the distributer brush arm 22 may be positively driven by a ratchet and pawl mechanism similar to the escapement mechanism illustrated.

At station B there is provided a rotary distributer 28, escapement mechanism v29, etc., which is similar to the mechanism described at station A. Connected to segments 31, 32, 33, 34 and 35 of distributer 28 are receiving magnets 36, 37, 38, 39 and 40 respectively. Whenever any of the transmitter contacts 11 to 15 are closed and the distributers are set in operation corresponding receiving magnets 36 to 40 will be operated by current from source 45. For eXample,.

14 are closed, circuits will be completed sequentially from impedance 43 and 44, distributer ring 24, brush 23, segment 16, contact 11, to source of current 45, and frombrush 23, segment 19, contact 14 to source of current 45, thence by conductor 46, line L, conductor 41', toreceiving magnets 36 and 39, segments 31 and 34, respectively,brush 47, distributer ring 48, impedance 49 and 50 to ground at l. Circuits through other receiving mag-y nets would be established in a like manner by the'closure'of additional transmitter contacts. The receiving magnets maT7 be employedto operate selecting mechanism of a receiving printing telegraph or they may be employed in connection with any suitable receiving or recording` device. The generatory may 'befassumed, for example, to produce a low frequency signaling current of GO' or 7 5 cycles. If desired, a source of direct4 current battery may be substituted for signaling current in place of the alternating cuijjrent source 45.

Two sources of alternating currents from which the synchronizing oscillations 'arederived are represented ait 52 and 53. The generator 52l may be assumed, for example, toA generate a frequency of 400 cycles and the generator 53 may be assumed'y to generate a frequency of 404 cycles, although other frequencies may obviously be employed. These sources are arranged to impress Vcurrents on vthe line L which also earries they signaling currents and it is therefore necessary to provide suitable filters and amplifiers to prevent interference between the synchronizing currents and the signalingv currents and to enable the beat oscillations to effect the operation of the synchronizing mechanism.

The filter 55 comprising one orymore condensers 56 andinductive resistance 57 may bearranged to admit, for example, a minimuin of 150 cycles thereby admitting the assumed higher frequencies and not the signaling frequency'. Associated with the filter 55 is a repeater or combiner 58 which is a` three element vacuum tube ofthe audiou type and Which taires up the tvvo original frequencies and gives out in addition to tne original frequencies the summation of the two frequencies and the difference in the tivo frequencies or the beat frequency. The Filament of the repeater is heated by battery 5, the grid 3 is suo-led with negative potential by means oi battery 6 and Athe space current in the c circuit 2 is supplied by battery Connected to the output circuit Q of the repeater 58 is a filter `6,0 comprising a condenser 59 and inductive resistance 61 which is arranged to admitr` the beat frequency onlv, or in the present case say a maXimum of 5 cycles. These filtered beat oscillations are then sent into a vacuum tube amplifier 62 and amplified sufficiently to effect the operation of the distributer magnet 2,5. The magnet 25 is shown in the present instance as controlling the escapement mechanism of a continuously driven distributer, which may be frictionally connected to theshaft of a motor.

.At station are provided filters 54 and 65, a repeater and an amplifier 67 which correspond to filters 55 and (l0, repeater and amplifier 52, respectively at station A. Across the output circuits of filters 6() and 65 are. connected resistances andSl, respectively. 'lhese resistances are employed to permit the proper operation of repeaters 58 and 66. The filters, repeater and amplifier at station B are arranged to permit the beat oscillations to effect the operation of dis- 'buter magnet 68 and cause it to step a distributer il in synchronism with the dis-r tributer 21. The means provided at station B for VEltering, repeating` and amplifying the synchronizing currents is a duplication of that already described in connection vv'th station A, and therefore a detailed descrip? tion of the apparatus at station B is believed to oe unnecessary.

VJhile the magnets 25 and 68 are shown as controlling the escapemen-t mechanism ofV continuously driven distributer arms, the magnets may he employed to operate La Cour motors as are Well lrnoivn in the art or they may be employed to control the correctingmeclianism of a synchronizing system such as disclosed in a copending application, Serial No. 129,462 filed November 4, 1.9i@ for Paul M. Rainey. i

/lt station A is a filter 73 comprising -1 Lib condenser i4 and inductive resistance 43Handv and station B is a corresponding filter comprising condenser 76 andinductive resistance 40 and 50. Each of these filters. is arranged to admit only the signaling current (l cycles.

Associated with eachquadrant of thereceiving distributer is a pair of localsegments and T5 which may 4be utilized `4to conduct current from battery T9 over the distributer brush to a printing magnet'y (not shown) to record the characters as determined or set up by the selective operation of the magnets 36 to 40, inclusive. i

"1 is invent-ion is not-limited to the emvlent of the particular synchronizing r l. scies designated or tothe particular type of synchronizing lapparatus illustratedl but is inten-ded to cover broadly t ie employnent of beat oscillations or the oscillations produced by the combination of a plurality of unequal current frequencies for maintainingl synchronism' between a plurality of movalole members.

What is claimed is:

1. The method of maintaining synchronism between tivo rotatable members'oper- "atively4 interconnected by a transmission line and adapted to be operated by independent ':illations or, for example, a maximum of1 K sources of motion `which consists in sending over said line currents of dierent frequencies, and employing the beat oscillations produced by combining said frequencies to control the operation of said rotatable members.

2. Electrical synchronizing apparatus comprising mea-ns for impressing on a line circuit currents of predetermined character, means for combining thev currents to produce beat oscillations, and means controlled by the beat oscillations for maintaining synchronism.

3. In a synchronizing system the combination of a transmission line, means for applying currents of different frequencies to said line, a plurality of members to be synchronized, and meansv responsive to the beat oscillations produced by said `different frequencies for controlling the operation of said members.

4. In a synchronizing system the combination of a transmission line, means for applying currents of different frequencies to sald line, a plurality of rotatable niembers, devices for controlling the rotation of said members, and means responsive to the beat oscillations produced by said currents for operating said devices.

5. Electrical synchronizing apparatus comprising a sending station and a receiving station, a transmission line interconnect-- ing said stations, distributer mechanism at each of sa-id stations, means for impressing upon the line a plurality of currents of different frequencies, means for altering the frequency of said currents, and means responsive to the altered frequency for Vcontrolling the said distributers.

6. Electrical synchronizing apparatus `comprising a sending station and a receiving station, means at the sending station for transmitting groups of signaling impulses, means at the receiving station responsive to the impulses transmitted from the sending station, independently driven distributers at each of said stations, means for transmitting a plurality of synchronizing currents of different frequencies, means at each of said stations for separating the signaling currents from the synchronizing currents, means at each of said stations for altering the synchronizing currents, and means at each of said stations responsive to the altered currents for operating said distributers in synchronism.

7. Electrical synchronizing apparatus comprising a' transmitting station and a receiving station interconnected by a transmission line, movable members at each of said stations, means at the transmitting station for transmitting signa-ling impulses, means Vfor superimposing on the signaling impulses currents of high frequency, means at the receiving station responsive to the signaling impulses, and means at each of said stations responsive to the high frequency currents for maintaining said members in synchronism.

8. Electrical apparatus comprising a sending station and a receiving station, means at the sending station for transmitting groups of signaling impulses, means at the receiving station responsive to the impulses transmitted from the sending station, electromagnetic apparatus at each of said stations, means for transmitting a plurality of currents of different frequencies, means at each of said stations for separating the signaling currents from the said currents of. different frequencies, means at each of said stations for altering said currents of different frequencies and means at each of said stations responsive to the altered currents for operating said electromagnetic devices.

9. A line section, two pairs of current paths electrically associated respectively withthe terminals of said section, ltering means at each terminal of said section to prevent current lying in one band of frequencies from flowing in one of said y aths and current lying in a second band o frequencies from flowing in the other of said paths at that terminal, means for impressing upon said line section a composite current Wave comprising two and only two sinusoidal components, said components lying within one of said frequency bands, means responsive to the conjoint action of said components, and means for generating and impressing upon said line section current waves lying Within the other of said bands of frequencies.

10. A line section, two pairs of current paths electrically associated respectively with the terminals of said section, filtering means at each terminal of said section to prevent current lying in one band of frequencies from liowing in one of said paths and current lying in a second band of frequencies from flowing in another of said pathsr at the same terminal, means for impressing upon said line section a composite current wave comprising two and only two sinusoidal components, said components lying within one of said frequency bands, and a wave distorting means at one terminal of said line section remote from said point for combining said sinusoidal components tol produce an electromotive force of frequency within the second of said band of frequencies, means selectively responsive to the electromotive force of the frequency produced by said distorting means, and means for generating and impressing upon said line section current waves lying within the second of said bands of frequencies.

11. A line section, separate pairs of current paths electrically associated With the terminals resoectivel of `said line section L A ,i lilterino' ineans at each end or d secu; f

C to divert current lying in ene i' andoi quencies to one o' said paths and .lying in a second band of frequencies to another of said paths, ineans for impressing upon said line section a composite current Wave comprising two and only two sinusoidal components, said components lying` Within one of said frequency hands, Wave distorting means at one end of said line section reniote frein said point for combining said sinusoidal components to produce an electroinotive force of frequency different than either of said components, means selectively responsive to the electroniotive torce of sai'cl last-nientioned frequency controlled by said last-mentioned electroniotiye force, and means for generating and impressing upon said line section current Waves lying Within the other of said bands of frequencles.

12. A line section, a pair of current pathsv electrically associated respectively with the terminals of said line section, iiltering at each terminal of said section to preynrt 'rrent 1ying in one hand ot' lireqaciicies vnein flowing in 'one of said paths and current lying in a second hand oi: `trequencies from iiowing in another of said paths at the saine terminal, separate generators for generating two sinusoidal Waves o1 different :trequei cies respectively, said frequencies lying Within one oi? said l-ifreqnency hands, ineans remote troni said generators operated by the conjoint action or' said Waves of different frequency, and nieans 'tor generating' and inugressing,` upon said line section current Waves lying Within the second of -said band ci frequencies.

The combination of a transmission line, in ans for applying currents of differen. frequencies to said line, a plurality orn rotatable nienihers, devices Vor controllingl the rotation of said nieinhers, and means responsive to the heat oscillations produced by said currents for operating' said devices. In Witness whereof, I hereunto subscribe my narne this th day of April, 1923.

HENRY C. EGERTON. 

